Techno-economic analysis of a microalgae-based biorefinery network for biofuels and value-added products

Biorefineries have the potential to become economically competitive through the exploitation of all biomass conversion scenarios. This study presents a technoeconomic assessment of a microalgal biorefinery for the integrated production of biodiesel, biobutanol, and co-products acetone, ethanol, and glycerol. Pre-treatment stages include acid hydrolysis (AH) and solvent extraction (SX), in two different processing networks (Configuration 1: AH followed by SX; Configuration 2: SX followed by AH). The lowest Minimum Fuel Selling Price (MFSP) was attained by Configuration 1 ($2.11/kg total biofuel), which was 75 % and 11 % lower than the single-fuel biobutanol and biodiesel conversion scenarios, respectively. Sensitivity analysis showed that the feedstock costs, inlet rate, and solvent usage (SX), have the greatest effect on the MFSP. Results also showed that the selling price of biobutanol is highly sensitive to fluctuations in biodiesel prices, which may have implications on a growing fuels market with unpredictable supply and demand.